Air

Not to be confused with Air Bar.

Air is the default filling of everything between space and magma, filling all otherwise empty gaps in a world.

Air can be passed through easily but cannot be seen. It does not appear to move, thus there is no wind.

If a block is removed, even when not in contact with anything but other solid blocks and water, it will immediately be filled with air.

Not having its head in contact with air will cause a Blockhead to display its air bar and begin decreasing it.

Air extends to over 1000 blocks above the magma at the center of the world and above that is space.